Motor control circuit



Aug. 20, 1957 B. F. WILEY ETAL MOTOR CONTROL CIRCUIT 5 Sheets-Sheet 2 Filed Aug. 23, 1954 To VALVES vaya, AND .v4

INVENTORS B4 F.W|LEY F; H.CULL|SON v F/G. 3.

AT ToRNEYs Aug. 20, 1957 B. F. WILEY ETAL 2,803,197

. MOTOR CONTROL CIRCUIT Filed Aug. 23, 1954 5 Sheets-Sheet 3 To4 VALVES vzva AND v.,f -T- INVENToRs v B. FWILEY F/G. 4'. By F. H. cuLLlsoN ATTORNEYS MOTOR CONTROL CIRCUIT Bruce F. Wiley and Frederick H. Cullison, Bartlesville,

Okla., assgnorsy to Phillips Petroleum Company, a cerporation of Delaware Application August 23, 1954, Serial No. 451,328

7 Claims. (Cl. 10S-.233)

This invention relates to gas lift systems for flowing wells. I n one specific aspect it relates to electrical systems. to operate selectively a plurality of motors positioned at a remote location by use of a minimum number of connecting circuits.

When gas pressure has diminished such that wells can no` longer be produced by the natural reservoir pressure,I it is often possible to remove additional oil by supplementing the natural formation pressure with compressed gas which is forced into the well from the surface. Such a system is referred to as a gas lif These systems are commonly used in oil producing operations, particularly during the stage of production betweent the period of free flow and the time when the wells must be pumped mechanically. In its simplest form, a gas lift involves expanding, gas into the oil column to lighten the column to an extent such that the formation pressure is suicient to sustain flow. Gas normally is introduced into the annular space between the tubing and casing to exert a downward pressure on the oil within this annular space, thereby forcing oil upwardly inside the tubing. The gas finally passes into the bottom of the tubing and in so doing becomes entrained in the oil in the tubing, thereby decreasing the specific gravity of the oil column.

It is often difcult to start the operation of a gas lift because of the high pressure require to balance the static column of fluid in the annular space between the tubing and casing. One system that has been proposed to operate a gas lift at lower initial pressure incorporates a plurality of kickoff values positioned at spaced intervals on the tubing. These valves communicate between the interior of the tubing and the annular space between the tubing and the casing. In this manner gas can be introduced into. the column of oil within the tubing whenever the column of oil rises above one of the valves. Thus, the column of oil within the tubing is lightened before the oil is removed completely from the annular space between the tubing and casing. In a system of this type it is desirable to be able to control the opening and closing of the valves independently of one another and independently of the pressure within the well.

In accordance with the present invention there is provided a novel electrical system to operate selectively a plurality of motor valves empioyed in a gas lift. The individual valves are actuated by reversible direct current motors which in turn are energized from a voltage source positioned at the surface of the well. The several motors are connected to the voltage source through respective tuned relays which are energized selectively by a control circuit connected to a tunable oscillator or to one of several oscillators of different frequencies. Each of the relays is tuned to a different frequency so that the several relays can be energized over a single control circuit.

Accordingly, it is anv object of this invention to provide an electrical system for operating a plurality of motors ICC selectively over a single. connecting circuit by the use of tuned relays.

Another object is to provide a system for energizing selectively from the surface of the earth a plurality of motor valves in a well by the use of a minimum number of connecting cables.

Other objects, advantages and features of this invention should become apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

Figure 1 is a schematic representation of a well having a gas lift system positioned therein;A

Figure 2 is a detailed view ofk a suitable motor operated valve for use in thesystem of Figure 1;

Figure 3 is a schematic circuit diagram of a first embodiment of the motor controly circuit of this invention; and

Figure 4 is a schematic circuit diagram of a second embodiment ofthe.l motor control circuit of this invention.

Referring now tothe drawing in detail and to' Figure 1 in particular therel is shown a casing 10 positioned within a well bore 11. The upper end of casing 10 protrudes from the wellf and. has a casing head 12 mounted thereon. Casing head 12 is provided with an inlet pipe 13 which supplies gas under pressure to the interior of casing 10. A tubing 14 extends axially through casing 10 and casing head 12. The upper end of tubing 14 is. connected` to a pipe 15' which conducts fluids from the well. The lower end of. tubing 14 has a screen 16 over the endV thereof. A plurality of valves V1, V2, V3 and V4 is attachedto tubing 14 in spaced relation. These valves are electrically connected byv a cable 18 to a control circuit which is positioned at the surface in a housingy 17. When these valves are in open positions, respective passages are formed between the interior of tubing 14V and the annular region between tubing 14 and casing 10. AsA illustrated in Figure 1, the well fluid 2t) from a formation 21 initially is under sufficient pressure to rise in casing 1f0 to a level 22. This formation pressure is not sufficient to elevate the oil column to the surface.

In Figure 2 there is illustrated a suitable motory valve which can be employed` as valvesVi, V2V3vand V4. This particular motor valve does not form a part of the present invention per se. The valve is described and claimed in the copending application of C. Hf. Kangas, Serial No. 443,540, filed July 15, 1954. For this reason the motor valve of- Figure 2 willbe described herein only in sufficient detail to explain the operation of the present invention. The valve assembly includes a housing 30 which is provided with an inlet port 31 which communicates with the annularv space between tubing 14 and casing 10. An outlet port 32 communicates with the interior of tubing 14 through a suitable opening in the tubing.y A plunger 33 is disposed to block the. passage,y between ports 31 and 32 in a first position and to allow fluid liow between these ports in a second. position. The upper end of plunger 33 is pivotally attached to a first lever 34 which rotates in a recess 35. The second end of lever 34 is pivotally attached to the rst'end of a second lever 36.. The second end of lever 35 is pivotally attached at an intermediate. region of a lever 37. One end of lever 37 pivots about a support 33 While the second end thereof is pivotallyv attached to a sleeve 39 which is threaded on a shaft 40. Shaft 40 is' attached through a flexible coupling 45 and suitable gearing to the drive shaft of a reversible direct current motor 42. A first limit switch 43 is positioned to be engaged by sleeve 39 when plunger 33 blocks the passage between ports 31 and 32, and a second limit switch 44 is positioned to be engaged by sleeve 39 when plunger 33 is withdrawn from the passage between ports 31 and 32. It should be apparent from an inspection of Figure 2 that rotation of shaft 40 in a first direction lowers plunger 33 while rotation of shaft 40 in the opposite direction raises plunger 33. For example, rotation of shaft 40 in a rst direction moves sleeve 39 upwardly from the illustrated position. Flexible coupling 45 permits rotation of lever 37 about support 38.y This'movement lifts plunger 33. The illustrated linkage provides a powerful force to open and close the valve without the use of a large motor.

In the operation of the system shown in Figure l, gas is introduced into casing through pipe 13. The resulting gas pressure exerts a downward force on liquid which lowers level 22 and raises the corresponding uid level within tubing 14. When level 22 falls below valvc V1, this valve is opened to introduce gas into the interior of tubing 14. This gas thereby lightens the column of oil in tubing 14 above V1 and facilitates the raising of the column. Once level 22 falls below valve V2, valve V1 is closed and valve V2 is opened. The same procedure continues as the oil level is lowered progressively past valves V3 and V4. When the oil level is lowered below inlet screen 16, all of the gas lift valves are closed so that the gas pressure in casing 10 enters the bottom of tubing 14.

The electrical circuits of this invention are provided to open and close the gas lift valves selectively. While four valves are illustrated in Figure 1, it should be apparent that more or fewer valves can be used if desired. With reference to Figure 3, four oscillators 50, 51, 52 and 43 are provided. These oscillators produce signals of respective frequencies F1, F2, Fs and F4. Corresponding rst output terminals of oscillators 50, 51, 52 and 53 are connected to respective terminals d, c, b and a of a switch 55. Corresponding second output terminals of oscillators 50, 51, 52 and 53 are connected to ground. The movable arm 56 of switch 55 is mechanically coupled to the movable arm 57 of a second corresponding switch 58. Switch 58 is provided with terminals a', b', c and d which are connected to corresponding first terminals of the movable arms of respective double-pole double-throw switches S4, Sa, S2 and S1. Corresponding second terminals of the movable arms of these latter switches are connected to ground. A direct current vo-ltage source 60 is connected across corresponding first end terminals of each of switches S1, S2, S3 and S4. Arm 56 of switch 55 is connected through a switch 61 to a lead 62 which extends into well 11 through cable 18. Arm 57 of switch 58 is connected through an ammeter 63 to a lead 64 which also extends into well 11 through cable 18.

The downhole circuit associated with valve V1 comprises a tuned relay R1 which is actuated by electrical signals of frequency F1. Relay R1 comprises a vcoil 70 having one end terminal connected to lead 62. The second end terminal of coil 70 is grounded, which can be at tubing 14. A reed 71 is attached to a base 72 and extends into coil 70. Reed 71 is of such configuration as to vibrate within coil 70 when a signal of frequency F1 is applied to the coil. Base 72 is connected by a lead 73 to D. C. power lead 64. Base 72 is also connected to the movable arm '74 of limit switch 44. The stationary contact 75 of limit switch 44 is connected to the movable arm 76 of limit switch 43. The stationary contact 77 of limit switch 43 is connected to ground through a resistor 78 and the coil of a relay 79. A movable contact 80 is mounted on reed 71 to engage a stationary contact 81 momentarily when reed 71 vibrates. Contact 81 is connected to one end terminal of a resistor 82 and through the coil of relay 79. The second end terminal of resistor 82 is connected to one terminal of a capacitor 83, the second terminal of capacitor 83 being connected to ground. A lead 84 is connected between base 72 and one terminal of a switch 85 which is actuated by the coil of relay 79. The second terminal of switch 85 is connected to one terminal of reversible motor 42, the second terminal of motor 42 being grounded.

As illustrated in Figure 3, sleeve 39 of the motor valve is in engagement with limit switch 43 such that contacts 76 and 77 are broken. At this position, the valve is closed as illustrated in Figure 2. When it is desired to open valve V1, switches and 58 are moved such that respective terminals d and d' are engaged by respective switch arms 56 and 57. Switch S1 is moved to the righthand position, for example, such that the positive terminal of voltage source is connected to switch terminal d'. Switch 61 is then closed for a short period of time. This results in an electrical signal of frequency F1 being applied to coil of relay R1, which signal causes reed '71 to vibrate such that contact is made periodically between terminals 30 and 81. This results in condenser 83 being charged from lead 64 through relay R1 and :resistor 82. Current also liows through the coil of relay 79. Capacitor 83 discharges through the coil of relay 79 when contact between terminals 80 and 81 is broken, thus maintaining current flow through the coil of relay 79. Closure of switch by relay 79 results in power lead 64 being connected through lead 84 and switch 85 to motor 4Z. This starts rotation of motor 42 in the direction to raise plunger 33 and move sleeve 39 toward limit switch 44. As soon as sleeve 39 is moved out of engagement with limit switch 43, a circuit is completed between base 72 of relay R1 and ground through the coil of relay 79 and through limit switches 44 and 43 and resistor 78. This last mentioned circuit is in parallel with the circuit which includes motor 42. The circuit through limit switches 44 and 43 serves to lock relay 79 in a closed position such that motor 42 continues to operate even after switch 61 is opened. As previously mentioned, switch 61 is closed only momentarily to start motor 42. Motor 42 continues to rotate until valve V1 is opened fully, at which time sleeve 39 engages limit switch 44 to break contact between terminals 74 and 75. This deenergizes relay 79 and opens switch 85 to terminate rotation of motor 42. Of course, the rotation of motor 42 can be terminated at an intermediate position if desired merely by opening switch S1 to disconnect voltage source 60.

When it is desired to close valve V1, switch S1 is moved to the left-hand position so that the negative terminal of voltage source 60 is applied to switch terminal d. This negative voltage is then applied to motor 42 in the manner previously described, but rotates motor 42 in the reverse direction. Limit switch 43 terminates rotation of motor 42 in the reverse direction in the same manner as does limit switch 44 in the forward direction. The remaining valve control circuits are identical to that shown in conjunction with valve V1 except that valves V2, V3 and V4 are energized by respective oscillators 51, 52 and 53 and respective switches S2, S3 and S4.

In Figure 4 there is iilustrated a second embodiment of the motor control circuit of this invention. This second circuit utilizes only a single connecting cable. Oscillators 50, 51, 52 and 53 are replaced by a single tunable oscillator which provides output frequencies F1, F2, F3 or F4 when dial 101 is rotated to the indicated contacts. The output of oscillator 100 is applied through a switch 102 to the primary winding 103 of a transformer 104. Arm 57 of switch 58 is connected to one end terminal of the secondary winding 105 of transformer 104. The second end terminal of transformer winding 105 is connected to a single lead 106 which passes into well 11 through cable 18. In this manner, direct current from source 60 and the alternating current from oscillator 100 are transmitted into the well on a single cable and a return ground lead, which can be tubing 14. A capacitor 107 is connected between lead 106 and coil 70 of relay R1 to prevent direct current from voltage source 60 from entering coil 70. A choke coil 108 is connected in lead 73 to prevent alternating current from oscillator 100 from entering the motor circuit. Otherwise the downhole circuitry is identical to that shown in Figure 3 and the operation of this circuitry is the same. A choke coil can also be connected between transformer winding 104 and switch 58, if desired, to prevent interaction between oscillator 100 and voltage source 60.

In view of the foregoing description it should be apparent that there is provided in accordance with this invention an improved system for operating a plurality of motors selectively by the use of tuned relays. While this system is particularly useful in the operation of a gas lift in an oil well, it should be apparent that the principles of the invention are applicable to the control of other circuit elements which are positioned remotely from a control panel. The circuit is particularly useful because only one or two connecting cables are required to control a plurality of elements. While a plurality of switches Si, S2, S3 and S4 is shown in Figures 3 and 4, a single reversing switch is all that is needed. The plurality of switches is convenient, however, because the position of any given valve can readily be determined merely by observing the position of the associated switch.

While the invention has been described in conjunction with present preferred embodiments it should be apparent that the invention is not limited thereto.

What is claimed is:

1. Well flowing apparatus comprising, in combination, a string of well tubing positioned in a well, a plurality of direct current motor operated valves at spaced intervals on said tubing to control flow of fluids between the exterior and interior of said tubing, a source of direct current positioned at the surface of the well, a plurality of relays operated by currents of different frequencies, said relays being positioned within the well, means positioned at the surface of the well to supply currents of said different frequencies, first circuit means extending from said source of direct current to said relays, second circuit means extending to said relays from said means to supply currents, and a plurality of third circuit means in the well actuated by respective ones of said relays to connect said first circuit means to said motor operated valves.

2. The combination in accordance with claim 1 wherein said first and second circuit means extend through the well as a single pair of conductors.

3. The combination in accordance with claim 1 further comprising means at the surface of the well to reverse the polarity of said source of direct current across said first circuit means.

4. The combination in accordance with claim 3 wherein said third circuit means each includes first and second limit switches through which the third circuit means is completed in part, said limit switches being positioned in spaced relationship with one another adjacent the motor of one of said motor valves, and means connected to the drive shaft of said motor to open said first and second limit switches when said motor rotates predetermined amounts in first and second directions, respectively, to open and close the associated valves, the opening of either limit switches thereby terminating rotation of the motor.

5. Well flowing apparatus comprising, in combination; a string of well tubing positioned in a well; a plurality of valves at spaced intervals on said tubing to control flow of fluids between the exterior and interior of said tubing; a direct-current motor to operate each of said valves; a

source of direct current positioned at the surface of the well; first circuit means extending from said source of direct current into the wellg'means positioned at the surface of the well to provide alternating currents of a plurality of frequencies, second circuit means extending from said last-mentioned means into the well; and a plurality of motor control circuits positioned in the well, each of said motor control circuits comprising a coil energized by said second circuit means, a reed positioned adjacent said coil so as to vibrate when a current of one of said plurality of frequencies is applied to said coil, first and second limit switches positioned adjacent one of said motors, means connected to the drive shaft of said one motor to open said first and second limit switches when said motor rotates predetermined amounts in first and second directions, respectively, tosopen and close the associated valve, a first contact on said reed connected to one conductor of said first circuit means, a second contact positioned to be engaged by vibration of said reed to complete connection with said first contact, a relay having one terminal of its coil connected to said second contact and its second terminal connected to the second conductor of said first circuit means, a circuit including the switch of said relay connecting said one motor across said first circuit means, and a second circuit connecting said first and second limit switches and the coil of said relay in series with said source of direct current through said first circuit means.

6. Well flowing apparatus comprising, in combination, a string of well tubing positioned in a well, a plurality of motor operated valves at spaced intervals on said tubing to control flow of fluids between the exterior and interior of said tubing, a source of electrical energy positioned at the surface of the well, a plurality of relays operated by currents of different frequencies, said relays being positioned within the well, means positioned at the surface of the well to supply currents of said dierent frequencies, first circuit means extending from said source of electrical energy to said relays, second circuit means extending to said relays from -said means positioned at the surface of the well to supply currents, and a plurality of third circuit means in the well actuated by respective ones of said relays to connect said first circuit means to said motor operated valves.

7. Well flowing apparatus comprising, in combination, a `string of well tubing positioned in a well, a plurality of motor operated valves at spaced intervals to control flow of fluids between the exterior and interior of said tubing, a plurality of first means to operate each of said valves when energized by an electrical current of a preselected frequency, means positioned at the surface of the well to provide currents of different frequencies to operate said valves, and circuit means to apply said currents selectively to said plurality of rst means.

References Cited in the file of this patent UNITED STATES PATENTS 161,739 Bell Apr. 6, 1875 1,635,779 Carter July 12, 1927 1,674,757 Bates June 26, 1928 1,922,711 Ortner Aug. 15, 1933 2,278,532 Crickmer Apr. 7, 1942 2,307,171 Tutton Jan. 5, 1943 2,540,144 Stern Feb. 6, 1951 

